Oxygen inhalation therapy has been employed as a most effective method of treatment for respiratory system diseases such as asthma, pulmonary emphysema or chronic bronchitis. In oxygen inhalation therapy, an oxygen concentrated gas is supplied to the patient. For this purpose, package-type oxygen concentrating apparatuses have been developed for use in the home. The package-type oxygen concentrating apparatus includes an oxygen concentrating unit for producing oxygen gas by separating nitrogen gas from the air, a compressor for supplying compressed air to the oxygen concentrating unit and a case for accommodating the oxygen concentrating unit and the compressor in order to insulate the noise. Japanese Unexamined Patent Publications (Kokai) No. 62-140619 and No. 63-218502 disclose examples of such apparatuses.